I bought this lens as a back up to my 24-70L and have used it as a main lense after looking over the IQ. Very hard to tell from the 24-70L, maybe a bit warmer, but a non issue. All I can say is wow. The contrast is just awsome. The focusing is not quite as fast as the 24-70L, but it a much smaller lighter lense also. Not to loud for a sigma. Zoom creep is present, but that is not a problem for me either, as I pay atention to what is going on as I shoot. Give this lens a try, it is well worth it.